The invention has been developed in connection with processing aspen trees and stacking the produced short logs (called "bolts") in logging operations conducted in Northern Alberta. The conventional steps practiced and the equipment used in that operation will now shortly be described, to identify some of the shortcomings that the present invention solves. However, in so doing it is to be understood that the invention is not to be limited in application to processing aspen.
In connection with such logging, the trees are cut and then skidded to the side of the logging road. Here they are placed with their butt ends at the road edge and their stems extending generally perpendicularly from the road. A machine, referred to as a de-limber, comes along and grasps each tree with two annular sets of arms. The outermost arms have de-limbing knives on their edges and are carried by a telescoping boom. The innermost arms are carried by the machine and are stationary. The outermost arms grasp the tree, part way up its stem, and place the butt into the innermost arms, which firmly grasp the butt. The outermost arms are then partially loosened and are stroked up the tree by the boom. It may require two or more strokes of the boom to de-limb the stem to a pre-determined diameter. The outermost arms are then further closed, to cut off the remaining unscraped tree top. The outermost arms are then moved back partway along the stem, the innermost arms are released and the stem is dropped to the ground.
At this stage, the de-limbed stems may be loaded onto a truck and sent to the mill for further processing. Or alternatively, they may be further processed at the logging site by cutting them into 8 foot long bolts.
The bolt-forming step in the field involves use of a second machine, referred to as a "slasher". The slasher has an arm that picks up the de-limbed stem with a grapple, rotates it through 90.degree. so that it is aligned with the road, and then advances the stem longitudinally until its end contacts a butt plate. A cutting element, spaced 8 feet from the butt plate, then moves into engagement with the stem and cuts it to form a bolt. The bolt drops into a "basket". The advancement and cutting process is then repeated. Once the basket is filled with bolts, the slasher arm is actuated to pick up the logs in the basket, rotate them through 90.degree., and then place them in piles on the road edge, ready to be loaded on a truck.
From the foregoing, it will be noted that the conventional system involves a significant number of machine movements, such as:
picking up the tree from the skidded tree pile; PA1 two-way travel of the tree stem during delimbing; PA1 laying the de-limbed stem down in a separate pile; PA1 picking up the de-limbed stem with the slasher and rotating it 90.degree. to align it with the slasher; and PA1 positioning the basket load of bolts at the side of the road. PA1 Except when first beginning, the bolts being biased into the stacking bin encounter a stack of bolts already in the bin chamber. This stack of bolts has frictional contact with the ground surface. Thus, the newly entering bolts encounter resistance and have to be driven with some force into the stack; PA1 The bolts in the stacking bin are closely confined at each of their ends by the side walls of the bin; and PA1 The bolts being introduced into the bin are entering at or adjacent to ground surface (or at the base of the stack). PA1 A conventional articulated arm and grapple (known as a "knuckle boom log loader"), which is adapted to reach out and grasp one or more of the tree stems by their butt ends and drag them inwardly to position the butt ends over a processing head, at which point the grapple may then be opened to drop the butt ends into engagement with the processing head; and PA1 A processing head that is mounted on a pivoting and rotating support, so that the head may align itself with the one or more stems being processed. The head is adapted to engage and longitudinally advance the stem; simultaneously de-limb it; terminate advancement when the proper bolt length extends past a cutting element; and pivot the cutting element through the advanced stem to cut and form the bolts. More particularly, the processing head comprises: a pair of driven rolls that clamp onto the dropped stem and advance it axially; de-limbing means that encircle the advancing stem and scrape off the branches; a cutting element, such as a pivoting chain saw or circular saw, that is adapted to sever the stem; and means for interrupting the advance of the stem when the desired length has passed the saw, whereby the rolls are stopped and the saw is pivoted to cut and form the bolts, which drop into the hopper. PA1 The tree stem is handled only once, by advancing it longitudinally; PA1 The stem is de-limbed and cut into bolts in the course of the single longitudinal movement of the stem; PA1 The bolts remain aligned with the travel of the stem, so no re-orientation is involved; PA1 The processing of stems does not involve the grapple arm, so the operator may use the latter to pick up a second set of stems as the first set is being processed; and PA1 The stack of bolts issue from the rear end of the stacker as it moves ahead, without any requirement for machine movements (such as lifting and rotating baskets of bolts, as is the case in the prior art).
It is a preferred objective of the present invention to provide apparatus and processing steps which simplify the operations of de-limbing and cutting the trees to form bolts and assembling the bolts in a stacked condition amenable for loading onto trucks.
It is the main objective to provide a novel system for stacking bolts.